8.9 · Previews and the macros behind SwiftUI
Previews and macros are the tooling half of modern SwiftUI. They change how quickly you see a screen in every state, and how much boilerplate the framework hides.
Mental model. A preview is a screen rendered in a chosen state. If a view cannot be previewed in that state, its dependencies are too hidden.
Tooling
<code>#Preview</code> and the macros SwiftUI relies on.
- How do #Preview and the macros SwiftUI uses work, and what makes a view easy to preview?
#Preview is a freestanding macro: #Preview("Empty state") { ListView(items: []) } declares a preview that Xcode compiles and renders on the canvas, with no…
More in SwiftUI
- 8.1 · What a View is, and how SwiftUI knows which view is which
- 8.2 · The update loop, dependency tracking and the cost of body
- 8.3 · State, Binding, Environment and Observation
- 8.4 · onAppear, task, onChange and scenes
- 8.5 · The layout negotiation, stacks, GeometryReader, safe area and custom Layout
- 8.6 · Lists, ForEach and NavigationStack
- 8.7 · Animations, PhaseAnimator, Canvas and TimelineView
- 8.8 · Preference keys and coordinate spaces
- 8.10 · State, bindings, Observation and environment, checked by running them
- 8.11 · The order of events in a render, and what Swift 6 isolation means for views
- 8.12 · Sharing space, alignment guides, adaptive containers and grids, measured
- 8.13 · What a ViewBuilder produces, and saving and restoring a navigation path